In the late 1950s, the German-born engineer Bernard Friese, who has died of cancer aged 82, joined forces with Giles Smith, a village butcher, to conceive and build the only truly Welsh sports car. It took its name, the Gilbern, from its creators' first names: the neat glass-fibre bodied coupes first appeared in 1959 and continued until 1973, when the arrival of VAT made build-it-yourself sports cars much less attractive. Unusually for a component car, the Gilbern also made the transition to being fully built.
Friese was born in Marienwerder, east Prussia (now part of Poland), and joined the German army as a teenager. He was taken prisoner by the allies in 1944 in the Netherlands, and met his future wife, Betty (then 16), on one of his nightly forays over the fence of a PoW camp in Kent. They went on to have six children, before divorcing in the 1980s.
Having received word from his father that there was very little to return to in Germany, Friese stayed in Kent throughout the 50s, working for a coach-builder called Martins, making bodies for fire engines and lorries, and sports-car bodies for the ubiquitous Ford 8 and 10 in the new wonder material of glass fibre.
In 1956 he decided to move to south Wales to take a job as a washing-machine engineer, and it was here, in Church Village, near Pontypridd, that Friese met Smith, who also nurtured an ambition to build his own sports car. This was the era of the "special", when young men created exotic-looking roadsters based on cheap pre-war Ford 10s and Austin Sevens.
The resulting Gilbern GT was a cut above the average DIY special, because both men were keen to create something more accomplished and bespoke than a humble kit-car. Firms such as Lotus and Jensen had made glass-fibre bodywork respectable, even desirable, given that it did not rust. It was also ideal for low-volume production-runs because it did not require such expensive tooling.
The elegant little GT bore a passing resemblance to the contemporary Aston Martin DB4. In the great tradition of such specialist cars, it used suspension and drivetrain parts from a variety of mass-production cars and offered a choice of MG or Ford engines. But the solid space-frame chassis was to Friese and Smith's own design.
The first Gilbern factory was a room above a slaughterhouse. A pear tree had to be chopped down to get the first cars outside, but eventually larger premises were found near Llantwit Fardre.
The Gilbern car went through two further major developments that took it upmarket in search of greater profit margins. The 120mph Gilbern Genie of 1966 came with a completely new, more modern body, with small rear seats and the latest three-litre Ford V6 engine. In 1969 the Genie was renamed the Invader, with slightly revised styling and a walnut dashboard. But its £2,400 price tag highlighted Gilbern's vulnerability in the face of much cheaper competition, such as the Ford Capri. Gilberns sold at the rate of 100 cars a year at the height of their popularity, with famous owners who included the Prince of Wales and the actor Anthony Hopkins.
In 1968 Gilbern had been acquired by Ace Holdings, a company that made slot machines, and there was money available to develop the cars and more employees to build them; the payroll increased from 20 to 60. But the imposition of VAT put £700 on the price of these already expensive cars. The Invader Mark III, introduced in 1972 (with its trademark red Welsh dragon badge), was the last Gilbern and was offered as a fully built-up car, for a steep £2,393. The new owners' lack of feeling for the nuances of the sports-car-making business did not help Gilbern's cause: by the early 1970s its founders had left, and the factory closed in 1973 with just over 1,000 of all models having been built.
Friese felt he had proved his point when he moved on in 1969, having stayed on a year after the takeover, rarely reminiscing about his car-making days. He went on to build a 360-strong company called Morgan Marine in Llandybie, Carmarthenshire, which became one of the biggest suppliers of fibreglass to the building industry. After his second marriage, to Vanna, he lived for 14 years in Thailand, but spent his final year back in Wales in a hospice. A determined character who did not always see eye-to-eye with his partner in the car-building adventure, Friese kept in regular touch with his German family members.
Friese's eldest daughter, Karen, predeceased him. He is survived by two sons, Julian and Christian, and three daughters, Nicola, Gillia and Felicity, from his marriage to Betty; Vanna and her daughter Saiesan, whom he adopted; and a daughter, Amy, by his partner Nok Kaenyangwai.
• Bernard Hugo Friese, engineer, born 18 October 1927; died 30 September 2010
• This article was amended on Tuesday 16 November 2010. The village of Church was changed to Church Village.
